Is use of mechanical ventilation a reasonable proxy indicator for coma among Medicare patients hospitalized for acute stroke?

To ascertain whether use of mechanical ventilation on admission to the hospital is a proxy indicator of coma (i.e., very severe stroke) among acute stroke patients. A secondary analysis of data from a medical record review on a nationally representative sample of 2,824 Medicare patients, ages 65 years or older, who were hospitalized for stroke in 1982-1983 or 1985-1986 in 297 acute care hospitals in 30 areas within five geographically dispersed states. Use of mechanical ventilation on the first day of hospitalization was significantly associated with level of consciousness on admission: < 2 percent of noncomatose patients versus 17.5 percent of comatose (p < .001). With a high specificity and high likelihood ratio for a positive test, use of mechanical ventilation on the first day of hospitalization ruled-in coma. It was also significantly associated with severity of illness, prognostic indicators (i.e., admission through the emergency room, admission to intensive care, and having a "do-not-resuscitate" order written during the hospital stay), and with in-hospital death. Adjusting for patient demographics, stroke type, comorbidity, and process of care, early initiation of mechanical ventilation remained significantly associated with both coma and in-hospital death. A stroke patient's use of mechanical ventilation on the first day of hospitalization is a valid proxy indicator of level of consciousness.